Unleashing The Demon Within
by VelocityRaptor
Summary: When Natsu supposedly dies killing Acnologia and protecting his friends, they thought he was lost forever. They were wrong. Two foes, two unlikely allies. Can Fairy Tail bother accepting help from a displaced demon guildmaster who turns out to be their greatest surprise? Oh who am I kidding. You all know Natsu is E.N.D. (Spoiler, I guess.)
1. Death of the Salamander

**I'm not sure if there will be a pairing.**

 **Unleashing The Demon Within**

* * *

As Acnologia struggled against Makarov in his full Titan form, everyone else began to make a mad dash for the ship. However, Natsu suddenly stopped and turned. Something within him is telling him to do the unthinkable.

"Gramps! Stay back!" he shouted.

"Natsu! Get out of here!" the master of Fairy Tail bellowed.

"I'm a Dragon Slayer! This is what I must do!"

The Salamander of Fairy Tail suddenly shrouded himself in flames. Not ordinary dragon flames. Rather, they were Zancrow's flames. He launches himself at the beast and it was not only knocked out of Makarov's grasp but also sent Acnologia flying back. Natsu was visibly in Dragon Force due to the scale-like patterns on his face and arms. He first flew to his master.

"Gramps." he said, before, to the old man's shock, giving him Igneel's scarf. "Give this to Lisanna. Looks like I won't be coming back.

"But why, Natsu?"

"Sometimes, it's the child who has to sacrifice themselves." he said coldly before flying back to face Acnologia. The Black Dragon was preparing to use its breath attack to wipe out Tenrou Island. Natsu stood strong even in the face of the strongest dragon in Earthland. He shrouds himself in both his and Zancrow's flames once again. This was the end not only for him, but for Acnologia.

"DRAGON SLAYER'S FORBIDDEN ART REVISION! FIRE DRAGON GOD'S FINAL FLAME!"

Natsu launched himself straight into Acnologia's mouth while his shroud of flames took on the shape of Igneel. The massive flames struck Acnologia's breath attack while it was still charging up, igniting them and causing a massive explosion that blew apart the dragon's face and sent the rest of its corpse to the sea. Natsu, however, was nowhere to be found.

"NATSU!"

The rest of the mages on Tenrou Island ran back to their guildmaster.

"Master!" Freed shouted.

"Grandpa. What happened? Where's Natsu?" Laxus asked. Makarov shuddered and slowly began to cry. He silently moved to Lisanna. He then gave her Igneel's scarf.

"Everyone. Natsu...he gave his life for all of us. To kill Acnologia."

In the span of a second, everyone was crying.

"N...Natsu's gone?" Lucy choked.

"I can't believe this. How could this happen?!" Gajeel bellowed, slamming his hand to the ground in anguish.

"H...H...H...HE NEVER EVEN SAID GOODBYE TO US!" Happy was beyond comforting now that his lifelong partner was gone.

"We must continue to live on, everyone. And not let his sacrifice go to waste."

With that, he started walking back to the ship. Everyone else was still crying before following him. Lisanna was still not moving. Instead, she clutched the scarf, fell to her knees and screamed.

"NATSU!"

* * *

After asking Lahar and Doranbolt for a trip back home and even told them what happened, to their surprise, they started to prepare for the Fire Dragon Slayer's funeral. Lisanna started wearing Natsu's scarf and moved to his place. The rest of the day, she was crying and crying on his hammock, along with Happy in her arms. It was only weeks later and the funeral was underway.

Everyone was holding back tears. Lucy was staring at the floor as her tears fell to the ground. Gray was also on the verge of tears and couldn't hold them back despite Juvia's efforts to help him. So far, only Happy and Lisanna weren't around for Natsu's funeral. Makarov began to speak, still crying.

"N...Natsu, was like a son to me. There were times where he would do something that gets into everyone's nerves. B...B...But he was a friend, protector, family. Therefore, we sha..."

He was interrupted by the sound of wing beats. Landing before the Fairy Tail mages as they turned around was the Fire Dragon King, Igneel.

"You. You're Igneel." Erza said.

"You think I would miss my son's funeral, mage?" the dragon said as-matter-of-factly.

"This dragon is not the only one here."

They looked back down. It was Yajima, Lahar, Doranbolt and the rest of the Magic Council.

"For his sacrifice. And for his deed of slaying the vilest dragon of all time," Yajima said. "he is given a place among the Ten Wizard Saints, taking the fourth rank." Igneel then interrupted him.

"He shall also be recognized as the Slayer of Acnologia. And shall be seen as an equal among the dragons. A Blood-Kin."

"The plaque that you shall place onto his monument, Master Makarov." Lahar said, giving the still-crying guildmaster the plaque. It said:

IN MEMORY OF

NATSU DRAGNEEL

SON OF IGNEEL

SLAYER OF ACNOLOGIA

ONE OF THE TEN WIZARD SAINTS

BLOOD-KIN OF ALL DRAGONS

"Please believe us." Lahar said. "The last part was the dragon's idea."

"Got a problem?" Igneel sneered.

Makarov attached the plaque on Natsu's monument. It was a statue of Natsu himself, fire on his right hand and Acnologia's head on the other.

"We shall be leaving now." Yajima said as the rest of the Magic council left. Only Igneel was still standing.

"Where is that scarf I gave him?"

"It's with Lisanna. She's so sad she couldn't get herself to go." Gray said.

"Explain to me who is this Lisanna." The Fire Dragon ordered.

* * *

Outside the house Natsu and Lisanna made as kids,

The youngest Take Over mage had created a gravestone for Natsu, replacing the one meant for herself. Igneel suddenly landed in front of the house, much to Lisanna's shock.

"Who are you?"

"Why I'm the father of your so-called boyfriend."

"You're Igneel? Why are you around here."

"I see no reason why I have to miss his funeral. That's not the reason I'm in front of you. I entrust his scarf to you. You've earned it.

"But why? Why can't you just take it?"

"Because you were the one closest to him when he was young. I shall be leaving. Farewell, Take Over mage. Live on for my son's sake."

With that, the Fire Dragon started flying off into the unknown.

* * *

A month after the funeral...

Four people were standing in front of Natsu's monument.

"This is what they made, huh?" the center person said.

"It seems these humans are quite willing enough to dedicate an expensive statue to one person." The one on his left said.

"But we have to move. It's only a matter of time before Mard Geer finds us. Should we wait for them?" another asked.

"Why should we?" the last one asked. "There's like 300 of them and 4 of us."

"Patience, everyone. Besides. I shall take responsibility both for this statue and for the little civil war I started within us."

"Why would that bastard defy you anyway?" one of them said, taking her hood off, revealing the face of a young woman with red eyes and black hair.

"Keep your hood up, Sayla." the others said to her.

"Shut up, Silver. Shut up, Tempesta. If fighting Mard Geer and our own is the Master's will, I shall follow."

"We didn't learn Transformation for nothing, you know." their leader said.

"As you wish, Master E.N.D." Silver said.

"You all know who I was, right?"

"Not really." Sayla and Tempesta said simultaneously. Silver then huffed and told them,

"Master E.N.D., is the slayer of the Black Dragon. He was the Salamander."

Sayla's and Tempesta's jaws dropped. E.N.D. turned to face them. He looked like Natsu except he had black and red eyes, demonic flame patterns that looked like red war paint around his eyes and pitch-black hair with a streak of orange and red.

"He's right. I was Natsu Dragneel."

* * *

 **Yeah. I'm trying here.**


	2. END Takes It Too Far

**Chapter 2: E.N.D. Takes it Too Far**

* * *

It has been 7 years since Natsu's "death". While most of Fairy Tail moved on, those who were very close to the Fire Dragon Slayer couldn't. Especially Lisanna, Gray, Lucy, Happy, Erza and Wendy.

Recently, there have been sightings of demons fighting each other. Unknown to them, the dark guild Tartarus was in a heated civil war between Mard Geer's and E.N.D.'s supporters.

Mard Geer was the self-proclaimed guild master of Tartarus and Underworld King following the start of the war. He has long thought that E.N.D.'s thoughts on human emotion have been "twisted" by the human within.

For E.N.D., however, this was not the case. And despite being the strongest demon in Tartarus, his faction was outnumbered and outgunned. They currently roam all of Fiore, in search of worthy allies to help the revived Dragon Slayer/dethroned guildmaster of Tartarus get his glory back. However, none have taken their challenge.

* * *

"Lisanna? You okay?" someone asked her. It was Levy.

"No." she replied, clutching the scaled scarf around her neck.

"I know it's hard to deal with but cheer up, will you? Listen. I'm going on a job with Gajeel, Lily, Jet and Droy. Wanna come?

"No thanks." Lisanna muttered.

Levy sighed, seeing that there was no hope for the young mage so she left with the others.

'Natsu. Please come back.' Lisanna thought to herself.

* * *

"Do we really have to stop for food, Master-"

Silver was interrupted when Sayla slapped him REALLY HARD.

"What was that for?!" he growled.

"We're about to go to a town FULL OF PEOPLE." the female demon reminded him. "Do you want them to know who we are?!"

"That's what she said." Tempesta butted in.

"Remain anonymous, guys." Natsu said.

They walked in though not much people noticed them.

"Where are we?" Tempesta asked.

"This is Hargeon." Natsu answered. "It's where I first met Lucy."

"You mean the blond girl with keys?" Silver asked.

"I thought you were smarter than a lowlife bandit, Silver?" Sayla teased him.

"I remember that restaurant where I knew more about Lucy. Follo-" Natsu, however, was interrupted when Tempesta patted his shoulder and pointed at a crowd's direction.

"Salamander's Back!" one of the girls screamed.

"The Slayer of Acnologia?!"

"Ladies. Ladies. One at a time."

Natsu was starting to get irritated.

"Master, your robes!" Sayla shouted.

The humanoid fire demon found out that he almost incinerated his disguise.

"Stand back. I'm gonna find out who it is." Natsu ordered.

The fire demon pushed through the crowd only to find Bora there. He was wearing a wig which made his hair look a lot like Natsu's. The true Salamander has had enough.

"Hey, Salamander. How did you slay Acnologia?" Natsu asked, acting innocent until the time was right.

"Why I just hit his heart with one of my most powerful spells: Hell Promine-"

Bora was cut off when Natsu punched him to a wall.

"Wrong. If I remember correctly, I blew his face off while I almost died."

"You blew his- Don't tell me! You're?" Bora's jaw dropped.

"Yes. I AM NATSU DRAGNEEL!"

The Tartarus demon burned his cloak off with a shroud of hot flames. Natsu's demonic black and red eyes broke the copycat's spirit. His serious death glare made him nervous. Lastly, his Fairy Tail mark was still there. However, his right elbow down to his hand was replaced for a scaled red version with claws (his hand is still shaped like a human's). The same applies for his left but it had a black Tartarus mark on his left shoulder.

Natsu's most notable feature now was his outfit. It was a scaly red leather vest with a black, demonic text that says: "E.N.D."

"You're actually the vilest of Zeref's demons?!" Bora screamed.

"Unless you want to pay the price for your use of an illegal magic, I suggest you give up. Or I grill you alive."

"NO PLEASE!"

"NOW LEAVE!"

The girls (and Bora) screamed random "It's E.N.D.! Run for your lives!" crap. Sayla, Tempesta and Silver took their hoods and cloaks off.

"That was not so necessary. Now Mard Geer will know where we are." Tempesta complained.

"Screw food. We go to Fairy Tail straight away."

"Halt!" someone yelled. It was the Rune Knights.

"Crap." Sayla muttered, taking a battle stance to protect E.N.D. with Silver and Tempesta.

"E.N.D.! A word, please!" It was Lahar.

After a few seconds of thought, Natsu/E.N.D. finally spoke.

"Very well. But leave my comrades alone." he said.

"But Master E.N.D.!"

"I'll be fine, Tempesta. You guys get to Fairy Tail and explain the civil war within Tartarus."

"No." Sayla said. "We stick together 'til the end."

With that, Natsu approached Lahar face-to-face. The Rune Knight then used Jutsu Shiki to create a field which prevents the demon from lying to him.

"Why do you look like Natsu Dragneel?" Lahar asked.

"Because I AM Natsu Dragneel." E.N.D. replied. Nothing happened.

"By the gods. What's going on here?"

"Tartarus is in a civil war. We've taken out two of our own kind. We need Fairy Tail's help in order to get through this." Again. Nothing happened.

"Why?"

"I would prefer to explain it to Master Makaro-"

"Makarov is gone, sir."

"I can't believe this. Damnit!"

"The current master is Macao Conbolt. Would you explain it all to him?"

"I guess."

"I'll let you and your friends go to Magnolia. Just don't cause a ruckus again."

With that, Lahar deactivated the enchantment and left with his squad. When the Tartarus demons were alone, Tempesta came up to E.N.D.

"So...are we still gonna eat?" Instantly, everyone's stomachs grumble.

"Everyone in town probably left. Let's eat in Magnolia." the fire demon told his comrade.

* * *

"Dad!" someone entered the guild hall. It was Romeo.

"What's wrong, son?" Macao asked. Romeo whispered something to his father's ear.

"There have been rumors of four demons here Magnolia. They say they know about Natsu."

This caught the ears of Lisanna and she ran out of the guild hall to investigate.

* * *

"Any info, Yakdoriga?" Sayla talked to the Communications Lacrima. Following the civil war start, the frog hybrid demon served as E.N.D.'s spy within Cube.

"Nope. Mard Geer did not take the deaths of Ezel and Franmalth lightly. Be on your guard. Also, Keyes fled somewhere. I don't know where but some minor members plan to hunt him down."

"I see. Thanks."

Sayla then turned off the Lacrima.

"Well, you're still in mortal danger, Silver." Tempesta chuckled.

"Not funny, Tempesta." the Ice Devil Slayer replied.

"Shush. I sense someone." E.N.D. scolded as the fire demon puts on his hood to hide his face. Sayla, Silver and Tempesta still had their cloaks to hide their Tartarus guild marks. There, Lisanna spoke,

"Do...you guys know about Natsu?" E.N.D. flinched.

"Well...for starters, I-"

Silver was interrupted by his master.

"Actually." the fire demon took off his hood, revealing Natsu's altered face.

"You're looking at him."

Lisanna's face was now flowing with tears since Natsu was here. In Front Of Her. A few seconds later, she tackles him with a bone crushing hug.

"NATSU!"

"Lisanna! You're choking me!"

"Talk about your hyperactive reunions, Master." Sayla chuckled.


	3. Reunion With The Fairies

**Chapter 3: Reunion with the Fairies**

* * *

Lisanna began asking a crap ton of questions in which everyone could barely keep up. It took Natsu, Silver, Sayla and Tempesta ten minutes to actually answer everything.

"Can you stop asking, Lisanna?" Natsu asked.

"Yeah, little lady. We can't spend the rest of our lives answering questions." Silver said.

"Oh. Sorry!" the Fairy Tail mage apologized.

Everyone started laughing.

"So who are your new friends, Natsu?" Lisanna asked.

"I can explain. Can you direct me to Erza?" Natsu replied.

"I guess."

The group began walking to the Fairy Tail guild hall.

* * *

"Have any of you guys seen Lisanna?" Mirajane asked.

"Nope." Freed, Bixlow, Evergreen and Laxus all said simultaneously.

The S-Class mage sighed at their answer.

As if on cue, Lisanna comes back and shouts out:

"Hey, guys! You're in for a surprise!"

Everyone turned their attention to the doorway, only for their mouths to gape when they see the altered face of Natsu and his three partners.

"Are...you...really?" Happy could barely speak.

Natsu flashed his signature grin. Everyone suddenly raised their arms and cried,

"NATSU!"

"Oh crap."

The humanoid fire demon ran like his life depended on it. Silver, Sayla and Tempesta simply sweat dropped.

* * *

The guild began celebrating Natsu's return as the three other Tartarus members introduced themselves. Gray was astonished to see his father again. Right on cue, Erza returns from a mission.

"What's all this noise about?!"

A tipsy Jet waltzed up to her. "Natsu's back!"

"What?!"

From the bar counter, the Fire Dragon Slayer turned around and waved his hand. "Oh. Hi, Erza!"

Natsu suddenly gets kicked in the gut by the S-Class Mage.

"What the hell was that for?!"

"Do you have any idea how secluded Lisanna and Happy were when you died?!"

"Uh...no?"

"Cut Natsu some slack, Erza." Gildarts said. "He just got here." he finished before continuing to drink with Tempesta and Macao.

"The type of bonds in this guild is strange." Sayla pondered.

Erza asked Natsu again, "Who's this? Your new girlfriend?" she teased.

The mage/demon's face reddened. "She is NOT my girlfriend!"

Natsu suddenly made a serious face. "Can I discuss something with you, Erza?"

"Why?"

"You might not believe it. So can Freed make a truth detector enchantment?"

* * *

Upstairs, Freed DOES make a truth detector enchantment (whoever lies will cause their hair to stand straight up.)

"So what is this about?" Erza asked.

"In reality, I'm a demon. I am E.N.D." Natsu coldly replied.

"Why didn't you say any of this earlier?"

"I only found out who I was years ago. It pains me to say this to you, Erza."

"I see. But who are those guys?" she asked, pointing her thumb to Sayla, Silver and Tempesta.

"Sayla and Tempesta are fellow demons. Silver, who is actually Gray's dad, is back to life due to another demon named Keyes. And that guy is nowhere to be seen."

"Anything el-"

"The dark guild Tartarus is in a civil war."

"Wait. Don't tell me that you're..."

"I am, or was, the guildmaster of Tartarus. The throne was taken by Mard Geer."

"Who's that? And why were you displaced?"

"When I died, I became one with my demonic form, allowing me to live. As a result, our memories, thoughts and personalities got mixed up. I ended up at Tartarus, spoke out against Mard Geer and the next thing I knew, civil war."

"Why didn't you fight back? You're E.N.D. for Pete's sake."

"Sometimes, numbers can win battles. That was the problem. Many Tartarus members spoke out against me because Mard Geer claimed that my beliefs on humans are 'twisted'. He says I'm no true demon. He's wrong. When I get back to Cube, I'll take him down, for now, I believe in a world where races of all appearances and powers can exist together."

"Natsu. You're putting us in danger here. You're putting EVERYONE in danger. Why request help from u-"

"Because I need you guys. How can I stand a chance if no other guild can aid m-"

"NATSU!" Someone shouted. It was Lisanna.

"Most of the Magic Council's been assassinated!"

Everyone gasped as the Take Over mage continued.

"It was said that the assailant is a man who can cause explosions at will!"

"Does it ring any bells, Natsu?" Erza asked.

"Yeah. It's Jackal. That guy always gets into everyone's nerves."


	4. Sparks of War

**Chapter 4: Sparks of War**

* * *

"Jack-Ass is the culprit?!" Silver yelled. "Gotta go, son. I've got a loud mouth to slay!"

"Wait, dad!" Gray shouted.

"What?"

"Do you even know where the Magic Council building even is?"

Then there was silence as the Ice Devil Slayer's jaw dropped. Suddenly, Natsu/E.N.D. flinched.

"I sense someone here in Magnolia. It might be Jackal judging by the scent!" he shouted.

"Let's check it out." Silver said.

"Right behind ya!" Laxus, Freed, Bixlow and Evergreen shouted in sync.

"Wait up!" Natsu shouted, suddenly conjuring wings of fire and grabbing Silver by the shoulder.

* * *

Meanwhile...

Jackal had attacked the 8-Island in Magnolia in search of Yajima.

"Oh...Yajima! Where are ya?! Haha!" he snarled as his Bomb Curse kept scaring people. The demon suddenly went flying to a building when Silver punched him in the face. He emerged from the rubble with a huge smile plastered on his face.

"Aha! A servant of the once mighty E.N.D. is a better catch than a former council member!"

"You're goin' down, pal. Ice Devil's Rage!"

Jackal dodges the attack and causes an explosion that engulfs Silver. The resulting blast is suddenly consumed by Natsu, much to Jackal's shock.

"Did you just consume an explosion?!" he shouted in a comedic way.

"Always know your opponent, Jack-Ass! Silver, you okay?"

The Devil Slayer came out without any visible injuries.

"I'm okay!"

'Gray's gonna have my head if something happened to his dad.' E.N.D. thought.

"Enough!" Jackal was preparing an attack but hesitated at the sight of E.N.D.

The displaced guildmaster launches himself at Jackal and launches a relentless assault of attacks. Even the defensive features of Jackal's curse didn't seem to faze Natsu as he just keeps eating them.

"Dragon Slayer Secret Art! Crimson Lotus: Exploding Flame Blade!"

The wild torrent of flames struck Jackal and sent him flying towards the ground.

"Do it, Silver! Finish him!"

"Right! Ice Devil's Zeroth Long Sword!"

Silver's blade struck Jackal and instantly froze him in place.

"Ha! Game Over!" Natsu shouted with triumph. By that time, the Thunder God Tribe and Tempesta had caught up to him.

"Well, that was quick." Laxus muttered.

"He has grown stronger, Laxus!" Bickslow said.

"I'm pretty sure it's because of who he really is." Evergreen told them.

Just when everyone thought it was over, Natsu flinched again.

"Wait. There's anoth..."

He was cut off when someone struck him and sent him to the ground. There, a strange demon emerged from the rubble with a smirk on her face.

"Kyoka!" Silver growled.

"Who?" Bickslow asked.

"Her curse/powers amplify or minimize the effects of your nerves. Like pain for instance."

Natsu emerges from the rubble, grabs Kyoka's face and drives his knee into it, breaking her mask and revealing her true, feminine face. She manages to escape by subduing everyone in sight with her curse.

"That's the third time she got away from us, Master!" Tempesta growled.

"We can take down frickin Jackal the Jack-ass but not Sayla's frickin ex-BFF!" Natsu bellowed.

"Mard Geer's found us. What do we do, Master E.N.D.?" Silver asked.

"We fight."

* * *

"That's suicide!" Macao yelled. Everyone at Fairy Tail began to panic about the impending threat of Mard Geer.

"Choose now, guys. None of this panic will help." Silver said.

"It's either we all run away and let Magnolia burn or fight back to the last man." Natsu said.

"Where the master goes, we go." Sayla said.

"Choose now, humans. Help us fight or run away." Tempesta commanded.

Then again, there was another scene of silence as everyone in the guild remained in deep thought. Suddenly, Gray stood up.

"I'll fight."

"Me too." Someone said. It was Mirajane.

Slowly, everyone rose up, accepting the risks to protect their beloved town. Suddenly, a man opened the doors frantically.

"There's something floating towards Magnolia!" he screamed.

* * *

When everyone got out, they saw a floating island with a menacing building on it.

"Cube. The Guild Hall of Tartarus." Natsu muttered.

"They'll all be there, Master. How should we proceed?" Tempesta asked.

"Turn all Fairy Tail members into cards, Cana." the Tartarus master said, turning to the card mage.

"Silver, Sayla, Tempesta and I will take a brunt of their attacks. Happy, Carla, Lily, carry the cards and release them on top of our enemies."

"A mix of an assault and a surprise attack, eh. I gotta admit, nice thinking, Salamander." Gajeel chuckled.

"But you're...you're gonna..." Wendy stuttered before regaining herself.

"-you might die, Natsu. We don't want to lose you again."

"I'm living through this one, Wendy. Don't worry. And besides. You've grown!"

* * *

The plan went into motion. Cana cast a spell that traps everyone in Fairy Tail sans Natsu in cards and given to the three Exceeds. Meanwhile, Natsu conjures wings of fire again and he grabs Silver and flies up. Sayla activated her full Etherious form and carries Tempesta up.

* * *

While this was happening...

Mard Geer sat on his throne, all bored. A demon later shows up in front of Mard Geer.

"We are ready to crush these insects, sir."

"Ah. Very good, Jiemma. My guild is nothing like your daughter, eh?"

"Yes. Sting and Rogue have blinded her with these pathetic 'feelings'! And those two dragons took away my guild, thinking that Sting can do a better job that me!"

"Then perhaps after our attack on this town is over...Sabertooth is next."

The two men laughed like maniacs before they heard panting.

"Sir!" someone called out. It was a large lizard demon.

"Torafusa? What's wrong?"

"We detected seven invaders! Master E.N.D., Silver, Sayla, Tempesta, and three flying cats!"

"PREPARE FOR BATTLE!"

And so, the final fight to decide who rules Tartarus begins.


End file.
